"Glenn Ashmore" wrote in
news:aNbJf.163191$WH.30518@dukeread01:

Is there a way to bring the field ground on a stock Yanmar alternator
out to a switch?



Nope....It's grounded to the case of the alternator. Sorry....

BTW, if you switch off the alternator's DC connection it may NOT turn off
the alternator, which may run on its own starting magnetism, anyway.

Lionheart has two 1-2-BOTH switches. The left switch switches the two
big L-16 bank house batteries, but does NOT switch the house 180A
alternator, which is separately connected directly to the batteries by a
huge diode isolator so the alternator cannot be connected to the house
(and of course a zillion dollars in electronics) without being connected
to the batteries.

The second switch is the battery switch for the Perkins 4-108 starter.
Position 2 connects the Perkins starter to its independent starting
battery. Position 1 has a very short jumper that connects the house
battery switch common to the starting switch position 1, so I can start
the engine off either house battery bank...or both house battery
banks...or the normally-connected starting battery...or everything-all-
connected-in-parallel-if-we-have-to....

The starting system's little 80A alternator is connected directly to the
starting battery, but should the house monster alternator fail, flipping
the battery switches to everything-all-connected-in-parallel-if-we-have-
to will charge all the banks from the 80A starting alternator, anyways.
Just set both battery switches to "BOTH" and it'll all charge
together....redundantly...(c;

Battery switches are located on the lip of the engine compartment cover
in the center cockpit of the Amel Sharki ketch, keeping all these heavy
cables really short. Power-R-Us....